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Chemical and mechanical properties of Q355NB steel grade spiral steel pipe
1、 Chemical composition
The chemical composition of Q355NB spiral steel pipe complies with the national standard GB/T 1591-2018 for low-alloy high-strength structural steel. The core elements and contents are as follows:
Carbon (C): ≤ 0.20%；
Silicon (Si): ≤ 0.50%；
Manganese (Mn): 0.90%~1.65% (enhances strength and hardenability);
Phosphorus (P) and sulfur (S): both ≤ 0.035% (strictly control impurities);
Alloy elements:
Niobium (Nb): 0.005%~0.05% (refine grain size, enhance toughness);
Vanadium (V): 0.01%~0.12%;
Titanium (Ti): 0.006%~0.05%;
Chromium (Cr) ≤ 0.30%, nickel (Ni) ≤ 0.50%, etc.
2、 Mechanical performance
Basic performance (related to thickness):
Yield strength (σ s):
Thickness ≤ 16mm: ≥ 355 MPa；
16~40mm：≥ 345 MPa；
40~63mm：≥ 335 MPa；
When the thickness is greater than 250mm, the lower pressure is ≥ 275 MPa;
Tensile strength (σ b): 470~630 MPa;
Post fracture elongation (δ 5): ≥ 21%.
Impact toughness (0 ℃ test):
Longitudinal impact energy: ≥ 34 J；
Lateral impact energy: ≥ 27 J；
Z-direction performance: Available in Z15/Z25/Z35 grades (with a cross-sectional shrinkage rate of ≥ 15%/25%/35% and resistance to laminar tearing).
Other performance:
Weldability: Low carbon equivalent, supports submerged arc welding, arc welding and other processes, thick plates need to be preheated;
Corrosion resistance: The surface can be coated or hot-dip galvanized, suitable for general industrial environments.
3、 Application Fields
Q355NB spiral steel pipe is mainly used in engineering scenarios under high load and low temperature environments:
Building structure: load-bearing frame of high-rise buildings, large-span venues;
Bridge engineering: Main beams of highways and railway bridges;
Mechanical manufacturing: heavy mechanical arm frames, engineering vehicle chassis;
Energy facilities: low-temperature storage tanks, oil and gas pipelines.
(Note: Specific parameters may be adjusted due to thickness, heat treatment process, and additional technical requirements.)
ADD：Chengnan Industrial Development Zone, Yanshan County, Hebei Province
Domestic phone number：0086-317-6689999
International call：0086-317-6165555
E-mail:9905791@qq.com
